1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
16 use syntax::{abi, ast, ptr, symbol};
17 use syntax::ast::{CrateSugar, ImplItem};
18 use syntax::codemap::{BytePos, Span};
22 use codemap::{LineRangeUtils, SpanUtils};
23 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
24 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented};
25 use config::{BraceStyle, Config, Density, IndentStyle};
26 use expr::{choose_rhs, format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs,
27 rewrite_call_inner, ExprType};
28 use lists::{definitive_tactic, itemize_list, write_list, DefinitiveListTactic, ListFormatting,
29 ListItem, ListTactic, Separator, SeparatorPlace, SeparatorTactic};
30 use rewrite::{Rewrite, RewriteContext};
31 use shape::{Indent, Shape};
32 use types::join_bounds;
33 use utils::{colon_spaces, contains_skip, end_typaram, first_line_width, format_abi,
34 format_constness, format_defaultness, format_mutability, format_unsafety,
35 format_visibility, is_attributes_extendable, last_line_contains_single_line_comment,
36 last_line_used_width, last_line_width, mk_sp, semicolon_for_expr, starts_with_newline,
37 stmt_expr, trim_newlines, trimmed_last_line_width};
38 use vertical::rewrite_with_alignment;
39 use visitor::FmtVisitor;
41 fn type_annotation_separator(config: &Config) -> &str {
42 colon_spaces(config.space_before_colon(), config.space_after_colon())
45 // Statements of the form
46 // let pat: ty = init;
47 impl Rewrite for ast::Local {
48 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
50 "Local::rewrite {:?} {} {:?}",
51 self, shape.width, shape.indent
54 skip_out_of_file_lines_range!(context, self.span);
56 if contains_skip(&self.attrs) {
60 let attrs_str = self.attrs.rewrite(context, shape)?;
61 let mut result = if attrs_str.is_empty() {
64 combine_strs_with_missing_comments(
69 self.attrs.last().map(|a| a.span.hi()).unwrap(),
78 let pat_shape = shape.offset_left(4)?;
80 let pat_shape = pat_shape.sub_width(1)?;
81 let pat_str = self.pat.rewrite(context, pat_shape)?;
82 result.push_str(&pat_str);
84 // String that is placed within the assignment pattern and expression.
86 let mut infix = String::with_capacity(32);
88 if let Some(ref ty) = self.ty {
89 let separator = type_annotation_separator(context.config);
90 let indent = shape.indent + last_line_width(&result) + separator.len();
92 let budget = shape.width.checked_sub(indent.width() + 1)?;
93 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
95 infix.push_str(separator);
96 infix.push_str(&rewrite);
99 if self.init.is_some() {
100 infix.push_str(" =");
106 result.push_str(&infix);
108 if let Some(ref ex) = self.init {
109 // 1 = trailing semicolon;
110 let nested_shape = shape.sub_width(1)?;
112 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
120 // TODO convert to using rewrite style rather than visitor
121 // TODO format modules in this style
124 keyword: &'static str,
125 abi: Cow<'static, str>,
126 vis: Option<&'a ast::Visibility>,
127 body: Vec<BodyElement<'a>>,
132 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
135 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
139 .map(|i| BodyElement::ForeignItem(i))
146 enum BodyElement<'a> {
147 // Stmt(&'a ast::Stmt),
148 // Field(&'a ast::Field),
149 // Variant(&'a ast::Variant),
150 // Item(&'a ast::Item),
151 ForeignItem(&'a ast::ForeignItem),
154 /// Represents a fn's signature.
155 pub struct FnSig<'a> {
156 decl: &'a ast::FnDecl,
157 generics: &'a ast::Generics,
159 constness: ast::Constness,
160 defaultness: ast::Defaultness,
161 unsafety: ast::Unsafety,
162 visibility: ast::Visibility,
167 decl: &'a ast::FnDecl,
168 generics: &'a ast::Generics,
169 vis: ast::Visibility,
175 constness: ast::Constness::NotConst,
176 defaultness: ast::Defaultness::Final,
177 unsafety: ast::Unsafety::Normal,
182 pub fn from_method_sig(
183 method_sig: &'a ast::MethodSig,
184 generics: &'a ast::Generics,
187 unsafety: method_sig.unsafety,
188 constness: method_sig.constness.node,
189 defaultness: ast::Defaultness::Final,
191 decl: &*method_sig.decl,
193 visibility: ast::Visibility::Inherited,
198 fn_kind: &'a visit::FnKind,
199 generics: &'a ast::Generics,
200 decl: &'a ast::FnDecl,
201 defualtness: ast::Defaultness,
204 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
208 constness: constness.node,
209 defaultness: defualtness,
211 visibility: visibility.clone(),
213 visit::FnKind::Method(_, method_sig, vis, _) => {
214 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
215 fn_sig.defaultness = defualtness;
216 if let Some(vis) = vis {
217 fn_sig.visibility = vis.clone();
225 fn to_str(&self, context: &RewriteContext) -> String {
226 let mut result = String::with_capacity(128);
227 // Vis defaultness constness unsafety abi.
228 result.push_str(&*format_visibility(&self.visibility));
229 result.push_str(format_defaultness(self.defaultness));
230 result.push_str(format_constness(self.constness));
231 result.push_str(format_unsafety(self.unsafety));
232 result.push_str(&format_abi(
234 context.config.force_explicit_abi(),
241 impl<'a> FmtVisitor<'a> {
242 fn format_item(&mut self, item: &Item) {
243 self.buffer.push_str(&item.abi);
245 let snippet = self.snippet(item.span);
246 let brace_pos = snippet.find_uncommented("{").unwrap();
249 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
250 // FIXME: this skips comments between the extern keyword and the opening
252 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
253 self.block_indent = self.block_indent.block_indent(self.config);
255 if item.body.is_empty() {
256 self.format_missing_no_indent(item.span.hi() - BytePos(1));
257 self.block_indent = self.block_indent.block_unindent(self.config);
258 let indent_str = self.block_indent.to_string(self.config);
259 self.push_str(&indent_str);
261 for item in &item.body {
262 self.format_body_element(item);
265 self.block_indent = self.block_indent.block_unindent(self.config);
266 self.format_missing_with_indent(item.span.hi() - BytePos(1));
271 self.last_pos = item.span.hi();
274 fn format_body_element(&mut self, element: &BodyElement) {
276 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
280 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
281 let item = Item::from_foreign_mod(fm, span, self.config);
282 self.format_item(&item);
285 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
286 let rewrite = item.rewrite(&self.get_context(), self.shape());
287 self.push_rewrite(item.span(), rewrite);
288 self.last_pos = item.span.hi();
298 ) -> Option<String> {
299 let context = self.get_context();
301 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
303 let (mut result, force_newline_brace) =
304 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
307 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
308 || last_line_width(&result) + 2 > self.shape().width
310 newline_brace = true;
311 } else if !result.contains('\n') {
312 newline_brace = false;
315 // Prepare for the function body by possibly adding a newline and
317 // FIXME we'll miss anything between the end of the signature and the
318 // start of the body, but we need more spans from the compiler to solve
322 result.push_str(&indent.to_string(self.config));
327 self.single_line_fn(&result, block).or_else(|| Some(result))
330 pub fn rewrite_required_fn(
334 sig: &ast::MethodSig,
335 generics: &ast::Generics,
337 ) -> Option<String> {
338 // Drop semicolon or it will be interpreted as comment.
339 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
340 let context = self.get_context();
342 let (mut result, _) = rewrite_fn_base(
346 &FnSig::from_method_sig(sig, generics),
352 // Re-attach semicolon
358 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
359 if fn_str.contains('\n') {
363 let codemap = self.get_context().codemap;
365 if self.config.empty_item_single_line() && is_empty_block(block, codemap)
366 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
368 return Some(format!("{}{{}}", fn_str));
371 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
373 if let Some(stmt) = block.stmts.first() {
374 match stmt_expr(stmt) {
376 let suffix = if semicolon_for_expr(&self.get_context(), e) {
382 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
384 .or_else(|| Some(self.snippet(e.span).to_owned()))
386 None => stmt.rewrite(&self.get_context(), self.shape()),
393 if let Some(res) = rewrite {
394 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
395 if !res.contains('\n') && width <= self.config.max_width() {
396 return Some(format!("{}{{ {} }}", fn_str, res));
404 pub fn visit_static(&mut self, static_parts: &StaticParts) {
405 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
406 self.push_rewrite(static_parts.span, rewrite);
409 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
410 let is_tuple = struct_parts.def.is_tuple();
411 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
412 .map(|s| if is_tuple { s + ";" } else { s });
413 self.push_rewrite(struct_parts.span, rewrite);
419 vis: &ast::Visibility,
420 enum_def: &ast::EnumDef,
421 generics: &ast::Generics,
424 let enum_header = format_header("enum ", ident, vis);
425 self.push_str(&enum_header);
427 let enum_snippet = self.snippet(span);
428 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
429 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
430 let generics_str = format_generics(
433 self.config.brace_style(),
434 if enum_def.variants.is_empty() {
435 BracePos::ForceSameLine
440 mk_sp(span.lo(), body_start),
441 last_line_width(&enum_header),
443 self.push_str(&generics_str);
445 self.last_pos = body_start;
447 self.block_indent = self.block_indent.block_indent(self.config);
448 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
450 Some(ref body_str) => self.push_str(body_str),
451 None => self.format_missing_no_indent(span.hi() - BytePos(1)),
453 self.block_indent = self.block_indent.block_unindent(self.config);
455 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
456 let indent_str = self.block_indent.to_string(self.config);
457 self.push_str(&indent_str);
460 self.last_pos = span.hi();
463 // Format the body of an enum definition
464 fn format_variant_list(
466 enum_def: &ast::EnumDef,
469 ) -> Option<String> {
470 if enum_def.variants.is_empty() {
473 let mut result = String::with_capacity(1024);
475 let indentation = self.block_indent.to_string(self.config);
476 result.push_str(&indentation);
478 let itemize_list_with = |one_line_width: usize| {
481 enum_def.variants.iter(),
485 if !f.node.attrs.is_empty() {
486 f.node.attrs[0].span.lo()
492 |f| self.format_variant(f, one_line_width),
498 let mut items: Vec<_> =
499 itemize_list_with(self.config.width_heuristics().struct_variant_width);
500 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
501 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
502 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
503 if has_multiline_variant && has_single_line_variant {
504 items = itemize_list_with(0);
507 let shape = self.shape().sub_width(2).unwrap();
508 let fmt = ListFormatting {
509 tactic: DefinitiveListTactic::Vertical,
511 trailing_separator: self.config.trailing_comma(),
512 separator_place: SeparatorPlace::Back,
514 ends_with_newline: true,
515 preserve_newline: true,
519 let list = write_list(&items, &fmt)?;
520 result.push_str(&list);
525 // Variant of an enum.
526 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
527 if contains_skip(&field.node.attrs) {
528 let lo = field.node.attrs[0].span.lo();
529 let span = mk_sp(lo, field.span.hi());
530 return Some(self.snippet(span).to_owned());
533 let context = self.get_context();
535 let shape = self.shape().sub_width(1)?;
536 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
541 .map_or(field.span.lo(), |attr| attr.span.hi());
542 let span = mk_sp(lo, field.span.lo());
544 let variant_body = match field.node.data {
545 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
547 &StructParts::from_variant(field),
549 Some(one_line_width),
551 ast::VariantData::Unit(..) => {
552 if let Some(ref expr) = field.node.disr_expr {
553 let lhs = format!("{} =", field.node.name);
554 rewrite_assign_rhs(&context, lhs, &**expr, shape)?
556 field.node.name.to_string()
561 let attrs_extendable = attrs_str.is_empty()
562 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
563 combine_strs_with_missing_comments(
575 context: &RewriteContext,
578 where_span_end: Option<BytePos>,
579 ) -> Option<String> {
580 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
581 let mut result = String::with_capacity(128);
582 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
583 let indent_str = offset.to_string(context.config);
584 let sep = format!("\n{}", &indent_str);
585 result.push_str(&ref_and_type);
587 let where_budget = if result.contains('\n') {
588 context.config.max_width()
590 context.budget(last_line_width(&result))
592 let option = WhereClauseOption::snuggled(&ref_and_type);
593 let where_clause_str = rewrite_where_clause(
595 &generics.where_clause,
596 context.config.brace_style(),
597 Shape::legacy(where_budget, offset.block_only()),
606 // If there is no where clause, we may have missing comments between the trait name and
607 // the opening brace.
608 if generics.where_clause.predicates.is_empty() {
609 if let Some(hi) = where_span_end {
610 match recover_missing_comment_in_span(
611 mk_sp(self_ty.span.hi(), hi),
612 Shape::indented(offset, context.config),
614 last_line_width(&result),
616 Some(ref missing_comment) if !missing_comment.is_empty() => {
617 result.push_str(missing_comment);
624 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
625 result.push_str(&where_clause_str);
626 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
627 result.push_str(&format!("{}{{{}}}", &sep, &sep));
629 result.push_str(" {}");
634 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
636 let width = offset.block_indent + context.config.tab_spaces() - 1;
637 let where_indent = Indent::new(0, width);
638 result.push_str(&where_indent.to_string(context.config));
640 result.push_str(&where_clause_str);
642 match context.config.brace_style() {
643 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
644 BraceStyle::AlwaysNextLine => result.push_str(&sep),
645 BraceStyle::PreferSameLine => result.push(' '),
646 BraceStyle::SameLineWhere => {
647 if !where_clause_str.is_empty() {
648 result.push_str(&sep);
657 let snippet = context.snippet(item.span);
658 let open_pos = snippet.find_uncommented("{")? + 1;
660 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
661 let mut visitor = FmtVisitor::from_context(context);
662 visitor.block_indent = offset.block_only().block_indent(context.config);
663 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
665 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
667 visitor.visit_impl_item(item);
670 visitor.format_missing(item.span.hi() - BytePos(1));
672 let inner_indent_str = visitor.block_indent.to_string(context.config);
673 let outer_indent_str = offset.block_only().to_string(context.config);
676 result.push_str(&inner_indent_str);
677 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
679 result.push_str(&outer_indent_str);
682 if result.ends_with('{') {
683 result.push_str(&sep);
693 fn is_impl_single_line(
694 context: &RewriteContext,
697 where_clause_str: &str,
700 let snippet = context.snippet(item.span);
701 let open_pos = snippet.find_uncommented("{")? + 1;
704 context.config.empty_item_single_line() && items.is_empty() && !result.contains('\n')
705 && result.len() + where_clause_str.len() <= context.config.max_width()
706 && !contains_comment(&snippet[open_pos..]),
710 fn format_impl_ref_and_type(
711 context: &RewriteContext,
714 ) -> Option<String> {
715 if let ast::ItemKind::Impl(
725 let mut result = String::with_capacity(128);
727 result.push_str(&format_visibility(&item.vis));
728 result.push_str(format_defaultness(defaultness));
729 result.push_str(format_unsafety(unsafety));
730 result.push_str("impl");
732 let lo = context.codemap.span_after(item.span, "impl");
733 let hi = match *trait_ref {
734 Some(ref tr) => tr.path.span.lo(),
735 None => self_ty.span.lo(),
737 let shape = generics_shape_from_config(
739 Shape::indented(offset + last_line_width(&result), context.config),
742 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
744 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
746 let polarity_str = if polarity == ast::ImplPolarity::Negative {
752 if let Some(ref trait_ref) = *trait_ref {
753 let result_len = result.len();
754 if let Some(trait_ref_str) = rewrite_trait_ref(
763 result.push_str(&trait_ref_str);
766 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
767 result.push_str(&rewrite_trait_ref(
778 result.push_str(&generics_str);
781 // Try to put the self type in a single line.
783 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
784 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
785 // If there is no where clause adapt budget for type formatting to take space and curly
786 // brace into account.
787 match context.config.brace_style() {
788 BraceStyle::AlwaysNextLine => 0,
794 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
795 // 1 = space before the type.
796 let budget = context.budget(used_space + 1);
797 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
798 if !self_ty_str.contains('\n') {
799 if trait_ref.is_some() {
800 result.push_str(" for ");
804 result.push_str(&self_ty_str);
809 // Couldn't fit the self type on a single line, put it on a new line.
811 // Add indentation of one additional tab.
812 let new_line_offset = offset.block_indent(context.config);
813 result.push_str(&new_line_offset.to_string(context.config));
814 if trait_ref.is_some() {
815 result.push_str("for ");
817 let budget = context.budget(last_line_width(&result));
818 let type_offset = match context.config.indent_style() {
819 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
820 IndentStyle::Block => new_line_offset,
822 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
829 fn rewrite_trait_ref(
830 context: &RewriteContext,
831 trait_ref: &ast::TraitRef,
837 ) -> Option<String> {
838 // 1 = space between generics and trait_ref
839 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
840 let shape = Shape::indented(offset + used_space, context.config);
841 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
842 if !(retry && trait_ref_str.contains('\n')) {
845 generics_str, polarity_str, &trait_ref_str
849 // We could not make enough space for trait_ref, so put it on new line.
851 let offset = offset.block_indent(context.config);
852 let shape = Shape::indented(offset, context.config);
853 let trait_ref_str = trait_ref.rewrite(context, shape)?;
857 &offset.to_string(context.config),
866 pub struct StructParts<'a> {
869 vis: &'a ast::Visibility,
870 def: &'a ast::VariantData,
871 generics: Option<&'a ast::Generics>,
875 impl<'a> StructParts<'a> {
876 fn format_header(&self) -> String {
877 format_header(self.prefix, self.ident, self.vis)
880 fn from_variant(variant: &'a ast::Variant) -> Self {
883 ident: variant.node.name,
884 vis: &ast::Visibility::Inherited,
885 def: &variant.node.data,
891 pub fn from_item(item: &'a ast::Item) -> Self {
892 let (prefix, def, generics) = match item.node {
893 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
894 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
902 generics: Some(generics),
909 context: &RewriteContext,
910 struct_parts: &StructParts,
912 one_line_width: Option<usize>,
913 ) -> Option<String> {
914 match *struct_parts.def {
915 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
916 ast::VariantData::Tuple(ref fields, _) => {
917 format_tuple_struct(context, struct_parts, fields, offset)
919 ast::VariantData::Struct(ref fields, _) => {
920 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
925 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
926 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
929 let mut result = String::with_capacity(128);
930 let header = format!(
932 format_visibility(&item.vis),
933 format_unsafety(unsafety),
937 result.push_str(&header);
939 let body_lo = context.codemap.span_after(item.span, "{");
941 let shape = Shape::indented(offset, context.config);
943 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
944 result.push_str(&generics_str);
946 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
947 if !type_param_bounds.is_empty() {
948 let ident_hi = context
950 .span_after(item.span, &format!("{}", item.ident));
951 let bound_hi = type_param_bounds.last().unwrap().span().hi();
952 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
953 if contains_comment(snippet) {
957 let trait_bound_str = rewrite_trait_bounds(
960 Shape::indented(offset, context.config),
962 // If the trait, generics, and trait bound cannot fit on the same line,
963 // put the trait bounds on an indented new line
964 if offset.width() + last_line_width(&result) + trait_bound_str.len()
965 > context.config.comment_width()
968 let trait_indent = offset.block_only().block_indent(context.config);
969 result.push_str(&trait_indent.to_string(context.config));
971 result.push_str(&trait_bound_str);
974 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
980 let where_budget = context.budget(last_line_width(&result));
981 let pos_before_where = if type_param_bounds.is_empty() {
982 generics.where_clause.span.lo()
984 type_param_bounds[type_param_bounds.len() - 1].span().hi()
986 let option = WhereClauseOption::snuggled(&generics_str);
987 let where_clause_str = rewrite_where_clause(
989 &generics.where_clause,
990 context.config.brace_style(),
991 Shape::legacy(where_budget, offset.block_only()),
999 // If the where clause cannot fit on the same line,
1000 // put the where clause on a new line
1001 if !where_clause_str.contains('\n')
1002 && last_line_width(&result) + where_clause_str.len() + offset.width()
1003 > context.config.comment_width()
1006 let width = offset.block_indent + context.config.tab_spaces() - 1;
1007 let where_indent = Indent::new(0, width);
1008 result.push_str(&where_indent.to_string(context.config));
1010 result.push_str(&where_clause_str);
1012 if generics.where_clause.predicates.is_empty() {
1013 let item_snippet = context.snippet(item.span);
1014 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1016 let comment_hi = body_lo - BytePos(1);
1017 let comment_lo = item.span.lo() + BytePos(lo as u32);
1018 if comment_lo < comment_hi {
1019 match recover_missing_comment_in_span(
1020 mk_sp(comment_lo, comment_hi),
1021 Shape::indented(offset, context.config),
1023 last_line_width(&result),
1025 Some(ref missing_comment) if !missing_comment.is_empty() => {
1026 result.push_str(missing_comment);
1034 match context.config.brace_style() {
1035 _ if last_line_contains_single_line_comment(&result) => {
1037 result.push_str(&offset.to_string(context.config));
1039 BraceStyle::AlwaysNextLine => {
1041 result.push_str(&offset.to_string(context.config));
1043 BraceStyle::PreferSameLine => result.push(' '),
1044 BraceStyle::SameLineWhere => {
1045 if !where_clause_str.is_empty()
1046 && (!trait_items.is_empty() || result.contains('\n'))
1049 result.push_str(&offset.to_string(context.config));
1057 let snippet = context.snippet(item.span);
1058 let open_pos = snippet.find_uncommented("{")? + 1;
1060 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1061 let mut visitor = FmtVisitor::from_context(context);
1062 visitor.block_indent = offset.block_only().block_indent(context.config);
1063 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1065 for item in trait_items {
1066 visitor.visit_trait_item(item);
1069 visitor.format_missing(item.span.hi() - BytePos(1));
1071 let inner_indent_str = visitor.block_indent.to_string(context.config);
1072 let outer_indent_str = offset.block_only().to_string(context.config);
1075 result.push_str(&inner_indent_str);
1076 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1078 result.push_str(&outer_indent_str);
1079 } else if result.contains('\n') {
1090 pub fn format_trait_alias(
1091 context: &RewriteContext,
1093 generics: &ast::Generics,
1094 ty_param_bounds: &ast::TyParamBounds,
1096 ) -> Option<String> {
1097 let alias = ident.name.as_str();
1098 // 6 = "trait ", 2 = " ="
1099 let g_shape = shape.offset_left(6 + alias.len())?.sub_width(2)?;
1100 let generics_str = rewrite_generics(context, generics, g_shape, generics.span)?;
1101 let lhs = format!("trait {}{} =", alias, generics_str);
1103 rewrite_assign_rhs(context, lhs, ty_param_bounds, shape.sub_width(1)?).map(|s| s + ";")
1106 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1107 let header_str = format_header(p.prefix, p.ident, p.vis);
1108 let generics_str = if let Some(generics) = p.generics {
1109 let hi = if generics.where_clause.predicates.is_empty() {
1112 generics.where_clause.span.hi()
1117 context.config.brace_style(),
1120 mk_sp(generics.span.lo(), hi),
1121 last_line_width(&header_str),
1126 Some(format!("{}{};", header_str, generics_str))
1129 pub fn format_struct_struct(
1130 context: &RewriteContext,
1131 struct_parts: &StructParts,
1132 fields: &[ast::StructField],
1134 one_line_width: Option<usize>,
1135 ) -> Option<String> {
1136 let mut result = String::with_capacity(1024);
1137 let span = struct_parts.span;
1139 let header_str = struct_parts.format_header();
1140 result.push_str(&header_str);
1142 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1143 let body_lo = context.codemap.span_after(span, "{");
1145 let generics_str = match struct_parts.generics {
1146 Some(g) => format_generics(
1149 context.config.brace_style(),
1150 if fields.is_empty() {
1151 BracePos::ForceSameLine
1156 mk_sp(header_hi, body_lo),
1157 last_line_width(&result),
1160 // 3 = ` {}`, 2 = ` {`.
1161 let overhead = if fields.is_empty() { 3 } else { 2 };
1162 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1163 || context.config.max_width() < overhead + result.len()
1165 format!("\n{}{{", offset.block_only().to_string(context.config))
1172 let overhead = if fields.is_empty() { 1 } else { 0 };
1173 let total_width = result.len() + generics_str.len() + overhead;
1174 if !generics_str.is_empty() && !generics_str.contains('\n')
1175 && total_width > context.config.max_width()
1178 result.push_str(&offset.to_string(context.config));
1179 result.push_str(generics_str.trim_left());
1181 result.push_str(&generics_str);
1184 if fields.is_empty() {
1185 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1186 if snippet.trim().is_empty() {
1188 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1190 result.push_str(snippet.trim_right());
1192 result.push_str(&offset.to_string(context.config));
1194 result.push_str(snippet);
1197 return Some(result);
1201 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1202 let one_line_budget =
1203 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1205 let items_str = rewrite_with_alignment(
1208 Shape::indented(offset, context.config).sub_width(1)?,
1209 mk_sp(body_lo, span.hi()),
1213 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1214 Some(format!("{} {} }}", result, items_str))
1220 .block_indent(context.config)
1221 .to_string(context.config),
1223 offset.to_string(context.config)
1228 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1229 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1230 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1231 fn get_bytepos_after_visibility(
1232 context: &RewriteContext,
1233 vis: &ast::Visibility,
1238 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1240 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1241 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1242 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1243 _ => default_span.lo(),
1247 fn format_tuple_struct(
1248 context: &RewriteContext,
1249 struct_parts: &StructParts,
1250 fields: &[ast::StructField],
1252 ) -> Option<String> {
1253 let mut result = String::with_capacity(1024);
1254 let span = struct_parts.span;
1256 let header_str = struct_parts.format_header();
1257 result.push_str(&header_str);
1259 let body_lo = if fields.is_empty() {
1260 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1261 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1265 let body_hi = if fields.is_empty() {
1266 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1268 // This is a dirty hack to work around a missing `)` from the span of the last field.
1269 let last_arg_span = fields[fields.len() - 1].span;
1270 if context.snippet(last_arg_span).ends_with(')') {
1275 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1279 let where_clause_str = match struct_parts.generics {
1281 let budget = context.budget(last_line_width(&header_str));
1282 let shape = Shape::legacy(budget, offset);
1283 let g_span = mk_sp(span.lo(), body_lo);
1284 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1285 result.push_str(&generics_str);
1287 let where_budget = context.budget(last_line_width(&result));
1288 let option = WhereClauseOption::new(true, false);
1289 rewrite_where_clause(
1291 &generics.where_clause,
1292 context.config.brace_style(),
1293 Shape::legacy(where_budget, offset.block_only()),
1294 Density::Compressed,
1302 None => "".to_owned(),
1305 if fields.is_empty() {
1307 let used_width = last_line_used_width(&result, offset.width()) + 3;
1308 if used_width > context.config.max_width() {
1310 result.push_str(&offset
1311 .block_indent(context.config)
1312 .to_string(context.config))
1315 let snippet = context.snippet(mk_sp(
1317 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1319 if snippet.is_empty() {
1321 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1322 result.push_str(snippet.trim_right());
1324 result.push_str(&offset.to_string(context.config));
1326 result.push_str(snippet);
1330 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1331 let fields = &fields.iter().collect::<Vec<_>>()[..];
1332 let one_line_width = context.config.width_heuristics().fn_call_width;
1333 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1336 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1337 && (result.contains('\n')
1338 || offset.block_indent + result.len() + where_clause_str.len() + 1
1339 > context.config.max_width())
1341 // We need to put the where clause on a new line, but we didn't
1342 // know that earlier, so the where clause will not be indented properly.
1344 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1345 .to_string(context.config));
1347 result.push_str(&where_clause_str);
1352 pub fn rewrite_type_alias(
1353 context: &RewriteContext,
1357 generics: &ast::Generics,
1358 vis: &ast::Visibility,
1360 ) -> Option<String> {
1361 let mut result = String::with_capacity(128);
1363 result.push_str(&format_visibility(vis));
1364 result.push_str("type ");
1365 result.push_str(&ident.to_string());
1368 let g_shape = Shape::indented(indent, context.config)
1369 .offset_left(result.len())?
1371 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1372 let generics_str = rewrite_generics(context, generics, g_shape, g_span)?;
1373 result.push_str(&generics_str);
1375 let where_budget = context.budget(last_line_width(&result));
1376 let option = WhereClauseOption::snuggled(&result);
1377 let where_clause_str = rewrite_where_clause(
1379 &generics.where_clause,
1380 context.config.brace_style(),
1381 Shape::legacy(where_budget, indent),
1389 result.push_str(&where_clause_str);
1390 if where_clause_str.is_empty() {
1391 result.push_str(" =");
1393 result.push_str(&format!("\n{}=", indent.to_string(context.config)));
1397 let ty_shape = Shape::indented(indent, context.config).sub_width(1)?;
1398 rewrite_assign_rhs(context, result, ty, ty_shape).map(|s| s + ";")
1401 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1403 if config.space_before_colon() { " " } else { "" },
1404 if config.space_after_colon() { " " } else { "" },
1408 pub fn rewrite_struct_field_prefix(
1409 context: &RewriteContext,
1410 field: &ast::StructField,
1411 ) -> Option<String> {
1412 let vis = format_visibility(&field.vis);
1413 let type_annotation_spacing = type_annotation_spacing(context.config);
1414 Some(match field.ident {
1415 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1416 None => format!("{}", vis),
1420 impl Rewrite for ast::StructField {
1421 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1422 rewrite_struct_field(context, self, shape, 0)
1426 pub fn rewrite_struct_field(
1427 context: &RewriteContext,
1428 field: &ast::StructField,
1430 lhs_max_width: usize,
1431 ) -> Option<String> {
1432 if contains_skip(&field.attrs) {
1433 let snippet = context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi()));
1434 return Some(snippet.to_owned());
1437 let type_annotation_spacing = type_annotation_spacing(context.config);
1438 let prefix = rewrite_struct_field_prefix(context, field)?;
1440 let attrs_str = field.attrs.rewrite(context, shape)?;
1441 let attrs_extendable = attrs_str.is_empty()
1442 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
1443 let missing_span = if field.attrs.is_empty() {
1444 mk_sp(field.span.lo(), field.span.lo())
1446 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1448 let mut spacing = String::from(if field.ident.is_some() {
1449 type_annotation_spacing.1
1453 // Try to put everything on a single line.
1454 let attr_prefix = combine_strs_with_missing_comments(
1462 let overhead = last_line_width(&attr_prefix);
1463 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1464 for _ in 0..lhs_offset {
1467 // In this extreme case we will be missing a space betweeen an attribute and a field.
1468 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1471 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1472 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1473 if let Some(ref ty) = orig_ty {
1474 if !ty.contains('\n') {
1475 return Some(attr_prefix + &spacing + ty);
1479 // We must use multiline. We are going to put attributes and a field on different lines.
1481 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1482 orig_ty = field.ty.rewrite(context, rhs_shape);
1483 let field_str = if prefix.is_empty() {
1486 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1488 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1491 pub struct StaticParts<'a> {
1493 vis: &'a ast::Visibility,
1496 mutability: ast::Mutability,
1497 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1498 defaultness: Option<ast::Defaultness>,
1502 impl<'a> StaticParts<'a> {
1503 pub fn from_item(item: &'a ast::Item) -> Self {
1504 let (prefix, ty, mutability, expr) = match item.node {
1505 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1506 ast::ItemKind::Const(ref ty, ref expr) => {
1507 ("const", ty, ast::Mutability::Immutable, expr)
1509 _ => unreachable!(),
1516 mutability: mutability,
1517 expr_opt: Some(expr),
1523 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1524 let (ty, expr_opt) = match ti.node {
1525 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1526 _ => unreachable!(),
1530 vis: &ast::Visibility::Inherited,
1533 mutability: ast::Mutability::Immutable,
1534 expr_opt: expr_opt.as_ref(),
1540 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1541 let (ty, expr) = match ii.node {
1542 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1543 _ => unreachable!(),
1550 mutability: ast::Mutability::Immutable,
1551 expr_opt: Some(expr),
1552 defaultness: Some(ii.defaultness),
1559 context: &RewriteContext,
1560 static_parts: &StaticParts,
1562 ) -> Option<String> {
1563 let colon = colon_spaces(
1564 context.config.space_before_colon(),
1565 context.config.space_after_colon(),
1567 let prefix = format!(
1569 format_visibility(static_parts.vis),
1570 static_parts.defaultness.map_or("", format_defaultness),
1571 static_parts.prefix,
1572 format_mutability(static_parts.mutability),
1578 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1579 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1581 if let Some(expr) = static_parts.expr_opt {
1582 let lhs = format!("{}{} =", prefix, ty_str);
1584 let remaining_width = context.budget(offset.block_indent + 1);
1589 Shape::legacy(remaining_width, offset.block_only()),
1590 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1591 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1593 Some(format!("{}{};", prefix, ty_str))
1597 pub fn rewrite_associated_type(
1599 ty_opt: Option<&ptr::P<ast::Ty>>,
1600 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1601 context: &RewriteContext,
1603 ) -> Option<String> {
1604 let prefix = format!("type {}", ident);
1606 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1608 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1609 let bound_str = bounds
1611 .map(|ty_bound| ty_bound.rewrite(context, shape))
1612 .collect::<Option<Vec<_>>>()?;
1613 if !bounds.is_empty() {
1614 format!(": {}", join_bounds(context, shape, &bound_str))
1622 if let Some(ty) = ty_opt {
1624 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1625 let lhs = format!("{}{} =", prefix, type_bounds_str);
1626 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1628 Some(format!("{}{};", prefix, type_bounds_str))
1632 pub fn rewrite_associated_impl_type(
1634 defaultness: ast::Defaultness,
1635 ty_opt: Option<&ptr::P<ast::Ty>>,
1636 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1637 context: &RewriteContext,
1639 ) -> Option<String> {
1640 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1643 ast::Defaultness::Default => Some(format!("default {}", result)),
1648 impl Rewrite for ast::FunctionRetTy {
1649 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1651 ast::FunctionRetTy::Default(_) => Some(String::new()),
1652 ast::FunctionRetTy::Ty(ref ty) => {
1653 let inner_width = shape.width.checked_sub(3)?;
1654 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1655 .map(|r| format!("-> {}", r))
1661 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1663 ast::TyKind::Infer => {
1664 let original = context.snippet(ty.span);
1671 impl Rewrite for ast::Arg {
1672 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1673 if is_named_arg(self) {
1674 let mut result = self.pat
1675 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1677 if !is_empty_infer(context, &*self.ty) {
1678 if context.config.space_before_colon() {
1679 result.push_str(" ");
1681 result.push_str(":");
1682 if context.config.space_after_colon() {
1683 result.push_str(" ");
1685 let overhead = last_line_width(&result);
1686 let max_width = shape.width.checked_sub(overhead)?;
1687 let ty_str = self.ty
1688 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1689 result.push_str(&ty_str);
1694 self.ty.rewrite(context, shape)
1699 fn rewrite_explicit_self(
1700 explicit_self: &ast::ExplicitSelf,
1702 context: &RewriteContext,
1703 ) -> Option<String> {
1704 match explicit_self.node {
1705 ast::SelfKind::Region(lt, m) => {
1706 let mut_str = format_mutability(m);
1709 let lifetime_str = l.rewrite(
1711 Shape::legacy(context.config.max_width(), Indent::empty()),
1713 Some(format!("&{} {}self", lifetime_str, mut_str))
1715 None => Some(format!("&{}self", mut_str)),
1718 ast::SelfKind::Explicit(ref ty, _) => {
1719 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1721 let mutability = explicit_self_mutability(&args[0]);
1722 let type_str = ty.rewrite(
1724 Shape::legacy(context.config.max_width(), Indent::empty()),
1729 format_mutability(mutability),
1733 ast::SelfKind::Value(_) => {
1734 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1736 let mutability = explicit_self_mutability(&args[0]);
1738 Some(format!("{}self", format_mutability(mutability)))
1743 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1744 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1745 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1746 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1753 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1754 if is_named_arg(arg) {
1761 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1763 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1764 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1765 _ => arg.ty.span.hi(),
1769 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1770 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1771 ident.node != symbol::keywords::Invalid.ident()
1777 // Return type is (result, force_new_line_for_brace)
1779 context: &RewriteContext,
1784 newline_brace: bool,
1786 ) -> Option<(String, bool)> {
1787 let mut force_new_line_for_brace = false;
1789 let where_clause = &fn_sig.generics.where_clause;
1791 let mut result = String::with_capacity(1024);
1792 result.push_str(&fn_sig.to_str(context));
1795 result.push_str("fn ");
1796 result.push_str(&ident.to_string());
1799 let overhead = if has_body && !newline_brace {
1806 let used_width = last_line_used_width(&result, indent.width());
1807 let one_line_budget = context.budget(used_width + overhead);
1809 width: one_line_budget,
1813 let fd = fn_sig.decl;
1814 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1815 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1816 result.push_str(&generics_str);
1818 let snuggle_angle_bracket = generics_str
1821 .map_or(false, |l| l.trim_left().len() == 1);
1823 // Note that the width and indent don't really matter, we'll re-layout the
1824 // return type later anyway.
1825 let ret_str = fd.output
1826 .rewrite(context, Shape::indented(indent, context.config))?;
1828 let multi_line_ret_str = ret_str.contains('\n');
1829 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1832 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1843 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1844 one_line_budget, multi_line_budget, arg_indent
1847 // Check if vertical layout was forced.
1848 if one_line_budget == 0 {
1849 if snuggle_angle_bracket {
1852 result.push_str("(");
1853 if context.config.indent_style() == IndentStyle::Visual {
1855 result.push_str(&arg_indent.to_string(context.config));
1861 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1862 && result.ends_with('(')
1867 // Skip `pub(crate)`.
1868 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1869 // A conservative estimation, to goal is to be over all parens in generics
1870 let args_start = fn_sig
1874 .filter_map(|p| match p {
1875 &ast::GenericParam::Type(ref t) => Some(t),
1879 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1880 let args_end = if fd.inputs.is_empty() {
1883 .span_after(mk_sp(args_start, span.hi()), ")")
1885 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1886 context.codemap.span_after(last_span, ")")
1888 let args_span = mk_sp(
1891 .span_after(mk_sp(args_start, span.hi()), "("),
1894 let arg_str = rewrite_args(
1897 fd.get_self().as_ref(),
1904 generics_str.contains('\n'),
1907 let put_args_in_block = match context.config.indent_style() {
1908 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1910 } && !fd.inputs.is_empty();
1912 let mut args_last_line_contains_comment = false;
1913 if put_args_in_block {
1914 arg_indent = indent.block_indent(context.config);
1916 result.push_str(&arg_indent.to_string(context.config));
1917 result.push_str(&arg_str);
1919 result.push_str(&indent.to_string(context.config));
1922 result.push_str(&arg_str);
1923 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1924 // Put the closing brace on the next line if it overflows the max width.
1926 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1929 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1932 // If the last line of args contains comment, we cannot put the closing paren
1933 // on the same line.
1937 .map_or(false, |last_line| last_line.contains("//"))
1939 args_last_line_contains_comment = true;
1941 result.push_str(&arg_indent.to_string(context.config));
1947 if let ast::FunctionRetTy::Ty(..) = fd.output {
1948 let ret_should_indent = match context.config.indent_style() {
1949 // If our args are block layout then we surely must have space.
1950 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1951 _ if args_last_line_contains_comment => false,
1952 _ if result.contains('\n') || multi_line_ret_str => true,
1954 // If the return type would push over the max width, then put the return type on
1955 // a new line. With the +1 for the signature length an additional space between
1956 // the closing parenthesis of the argument and the arrow '->' is considered.
1957 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1959 // If there is no where clause, take into account the space after the return type
1961 if where_clause.predicates.is_empty() {
1965 sig_length > context.config.max_width()
1968 let ret_indent = if ret_should_indent {
1969 let indent = if arg_str.is_empty() {
1970 // Aligning with non-existent args looks silly.
1971 force_new_line_for_brace = true;
1974 // FIXME: we might want to check that using the arg indent
1975 // doesn't blow our budget, and if it does, then fallback to
1976 // the where clause indent.
1981 result.push_str(&indent.to_string(context.config));
1985 Indent::new(indent.block_indent, last_line_width(&result))
1988 if multi_line_ret_str || ret_should_indent {
1989 // Now that we know the proper indent and width, we need to
1990 // re-layout the return type.
1991 let ret_str = fd.output
1992 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1993 result.push_str(&ret_str);
1995 result.push_str(&ret_str);
1998 // Comment between return type and the end of the decl.
1999 let snippet_lo = fd.output.span().hi();
2000 if where_clause.predicates.is_empty() {
2001 let snippet_hi = span.hi();
2002 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2003 // Try to preserve the layout of the original snippet.
2004 let original_starts_with_newline = snippet
2006 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2007 let original_ends_with_newline = snippet
2008 .rfind(|c| c != ' ')
2009 .map_or(false, |i| snippet[i..].ends_with('\n'));
2010 let snippet = snippet.trim();
2011 if !snippet.is_empty() {
2012 result.push(if original_starts_with_newline {
2017 result.push_str(snippet);
2018 if original_ends_with_newline {
2019 force_new_line_for_brace = true;
2025 let pos_before_where = match fd.output {
2026 ast::FunctionRetTy::Default(..) => args_span.hi(),
2027 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2030 let is_args_multi_lined = arg_str.contains('\n');
2032 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2033 let where_clause_str = rewrite_where_clause(
2036 context.config.brace_style(),
2037 Shape::indented(indent, context.config),
2043 is_args_multi_lined,
2045 // If there are neither where clause nor return type, we may be missing comments between
2047 if where_clause_str.is_empty() {
2048 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2049 match recover_missing_comment_in_span(
2050 mk_sp(args_span.hi(), ret_span.hi()),
2053 last_line_width(&result),
2055 Some(ref missing_comment) if !missing_comment.is_empty() => {
2056 result.push_str(missing_comment);
2057 force_new_line_for_brace = true;
2064 result.push_str(&where_clause_str);
2066 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2067 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2068 Some((result, force_new_line_for_brace))
2071 #[derive(Copy, Clone)]
2072 struct WhereClauseOption {
2073 suppress_comma: bool, // Force no trailing comma
2074 snuggle: bool, // Do not insert newline before `where`
2075 compress_where: bool, // Try single line where clause instead of vertical layout
2078 impl WhereClauseOption {
2079 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2081 suppress_comma: suppress_comma,
2083 compress_where: false,
2087 pub fn snuggled(current: &str) -> WhereClauseOption {
2089 suppress_comma: false,
2090 snuggle: trimmed_last_line_width(current) == 1,
2091 compress_where: false,
2097 context: &RewriteContext,
2099 explicit_self: Option<&ast::ExplicitSelf>,
2100 one_line_budget: usize,
2101 multi_line_budget: usize,
2106 generics_str_contains_newline: bool,
2107 ) -> Option<String> {
2108 let mut arg_item_strs = args.iter()
2109 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2110 .collect::<Option<Vec<_>>>()?;
2112 // Account for sugary self.
2113 // FIXME: the comment for the self argument is dropped. This is blocked
2114 // on rust issue #27522.
2115 let min_args = explicit_self
2116 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2117 .map_or(1, |self_str| {
2118 arg_item_strs[0] = self_str;
2122 // Comments between args.
2123 let mut arg_items = Vec::new();
2125 arg_items.push(ListItem::from_str(""));
2128 // FIXME(#21): if there are no args, there might still be a comment, but
2129 // without spans for the comment or parens, there is no chance of
2130 // getting it right. You also don't get to put a comment on self, unless
2132 if args.len() >= min_args || variadic {
2133 let comment_span_start = if min_args == 2 {
2134 let second_arg_start = if arg_has_pattern(&args[1]) {
2135 args[1].pat.span.lo()
2137 args[1].ty.span.lo()
2139 let reduced_span = mk_sp(span.lo(), second_arg_start);
2141 context.codemap.span_after_last(reduced_span, ",")
2146 enum ArgumentKind<'a> {
2147 Regular(&'a ast::Arg),
2151 let variadic_arg = if variadic {
2152 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2153 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2154 Some(ArgumentKind::Variadic(variadic_start))
2159 let more_items = itemize_list(
2161 args[min_args - 1..]
2163 .map(ArgumentKind::Regular)
2164 .chain(variadic_arg),
2168 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2169 ArgumentKind::Variadic(start) => start,
2172 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2173 ArgumentKind::Variadic(start) => start + BytePos(3),
2176 ArgumentKind::Regular(..) => None,
2177 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2184 arg_items.extend(more_items);
2187 let fits_in_one_line = !generics_str_contains_newline
2188 && (arg_items.is_empty()
2189 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2191 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2192 item.item = Some(arg);
2195 let last_line_ends_with_comment = arg_items
2198 .and_then(|item| item.post_comment.as_ref())
2199 .map_or(false, |s| s.trim().starts_with("//"));
2201 let (indent, trailing_comma) = match context.config.indent_style() {
2202 IndentStyle::Block if fits_in_one_line => {
2203 (indent.block_indent(context.config), SeparatorTactic::Never)
2205 IndentStyle::Block => (
2206 indent.block_indent(context.config),
2207 context.config.trailing_comma(),
2209 IndentStyle::Visual if last_line_ends_with_comment => {
2210 (arg_indent, context.config.trailing_comma())
2212 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2215 let tactic = definitive_tactic(
2217 context.config.fn_args_density().to_list_tactic(),
2221 let budget = match tactic {
2222 DefinitiveListTactic::Horizontal => one_line_budget,
2223 _ => multi_line_budget,
2226 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2228 let fmt = ListFormatting {
2231 trailing_separator: if variadic {
2232 SeparatorTactic::Never
2236 separator_place: SeparatorPlace::Back,
2237 shape: Shape::legacy(budget, indent),
2238 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2239 preserve_newline: true,
2240 config: context.config,
2243 write_list(&arg_items, &fmt)
2246 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2247 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2248 ident.node != symbol::keywords::Invalid.ident()
2254 fn compute_budgets_for_args(
2255 context: &RewriteContext,
2259 newline_brace: bool,
2261 force_vertical_layout: bool,
2262 ) -> Option<((usize, usize, Indent))> {
2264 "compute_budgets_for_args {} {:?}, {}, {}",
2270 // Try keeping everything on the same line.
2271 if !result.contains('\n') && !force_vertical_layout {
2272 // 2 = `()`, 3 = `() `, space is before ret_string.
2273 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2274 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2284 let one_line_budget = context.budget(used_space);
2286 if one_line_budget > 0 {
2288 let (indent, multi_line_budget) = match context.config.indent_style() {
2289 IndentStyle::Block => {
2290 let indent = indent.block_indent(context.config);
2291 (indent, context.budget(indent.width() + 1))
2293 IndentStyle::Visual => {
2294 let indent = indent + result.len() + 1;
2295 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2296 (indent, context.budget(multi_line_overhead))
2300 return Some((one_line_budget, multi_line_budget, indent));
2304 // Didn't work. we must force vertical layout and put args on a newline.
2305 let new_indent = indent.block_indent(context.config);
2306 let used_space = match context.config.indent_style() {
2308 IndentStyle::Block => new_indent.width() + 1,
2309 // Account for `)` and possibly ` {`.
2310 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2312 Some((0, context.budget(used_space), new_indent))
2315 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2316 let predicate_count = where_clause.predicates.len();
2318 if config.where_single_line() && predicate_count == 1 {
2321 let brace_style = config.brace_style();
2323 brace_style == BraceStyle::AlwaysNextLine
2324 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2327 fn rewrite_generics(
2328 context: &RewriteContext,
2329 generics: &ast::Generics,
2332 ) -> Option<String> {
2333 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2334 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2335 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2336 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2339 fn rewrite_generics_inner(
2340 context: &RewriteContext,
2341 generics: &ast::Generics,
2343 one_line_width: usize,
2345 ) -> Option<String> {
2346 // FIXME: convert bounds to where clauses where they get too big or if
2347 // there is a where clause at all.
2350 enum GenericsArg<'a> {
2351 Lifetime(&'a ast::LifetimeDef),
2352 TyParam(&'a ast::TyParam),
2354 impl<'a> Rewrite for GenericsArg<'a> {
2355 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2357 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2358 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2362 impl<'a> Spanned for GenericsArg<'a> {
2363 fn span(&self) -> Span {
2365 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2366 GenericsArg::TyParam(ty) => ty.span(),
2371 if generics.params.is_empty() {
2372 return Some(String::new());
2375 let generics_args = generics
2378 .filter_map(|p| match p {
2379 &ast::GenericParam::Lifetime(ref l) => Some(l),
2382 .map(|lt| GenericsArg::Lifetime(lt))
2383 .chain(generics.params.iter().filter_map(|ty| match ty {
2384 &ast::GenericParam::Type(ref ty) => Some(GenericsArg::TyParam(ty)),
2387 let items = itemize_list(
2392 |arg| arg.span().lo(),
2393 |arg| arg.span().hi(),
2394 |arg| arg.rewrite(context, shape),
2395 context.codemap.span_after(span, "<"),
2399 format_generics_item_list(context, items, shape, one_line_width)
2402 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2403 match config.indent_style() {
2404 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2405 IndentStyle::Block => {
2409 .block_indent(config.tab_spaces())
2410 .with_max_width(config)
2416 pub fn format_generics_item_list<I>(
2417 context: &RewriteContext,
2420 one_line_budget: usize,
2423 I: Iterator<Item = ListItem>,
2425 let item_vec = items.collect::<Vec<_>>();
2427 let tactic = definitive_tactic(
2429 ListTactic::HorizontalVertical,
2433 let fmt = ListFormatting {
2436 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2437 SeparatorTactic::Never
2439 context.config.trailing_comma()
2441 separator_place: SeparatorPlace::Back,
2443 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2444 preserve_newline: true,
2445 config: context.config,
2448 let list_str = write_list(&item_vec, &fmt)?;
2450 Some(wrap_generics_with_angle_brackets(
2457 pub fn wrap_generics_with_angle_brackets(
2458 context: &RewriteContext,
2460 list_offset: Indent,
2462 if context.config.indent_style() == IndentStyle::Block
2463 && (list_str.contains('\n') || list_str.ends_with(','))
2467 list_offset.to_string(context.config),
2470 .block_unindent(context.config)
2471 .to_string(context.config)
2473 } else if context.config.spaces_within_parens_and_brackets() {
2474 format!("< {} >", list_str)
2476 format!("<{}>", list_str)
2480 fn rewrite_trait_bounds(
2481 context: &RewriteContext,
2482 bounds: &[ast::TyParamBound],
2484 ) -> Option<String> {
2485 if bounds.is_empty() {
2486 return Some(String::new());
2488 let bound_str = bounds
2490 .map(|ty_bound| ty_bound.rewrite(context, shape))
2491 .collect::<Option<Vec<_>>>()?;
2492 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2495 fn rewrite_where_clause_rfc_style(
2496 context: &RewriteContext,
2497 where_clause: &ast::WhereClause,
2500 span_end: Option<BytePos>,
2501 span_end_before_where: BytePos,
2502 where_clause_option: WhereClauseOption,
2503 is_args_multi_line: bool,
2504 ) -> Option<String> {
2505 let block_shape = shape.block().with_max_width(context.config);
2507 let (span_before, span_after) =
2508 missing_span_before_after_where(span_end_before_where, where_clause);
2509 let (comment_before, comment_after) =
2510 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2512 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2515 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2518 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2520 let clause_shape = clause_shape.sub_width(1)?;
2521 // each clause on one line, trailing comma (except if suppress_comma)
2522 let span_start = where_clause.predicates[0].span().lo();
2523 // If we don't have the start of the next span, then use the end of the
2524 // predicates, but that means we miss comments.
2525 let len = where_clause.predicates.len();
2526 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2527 let span_end = span_end.unwrap_or(end_of_preds);
2528 let items = itemize_list(
2530 where_clause.predicates.iter(),
2533 |pred| pred.span().lo(),
2534 |pred| pred.span().hi(),
2535 |pred| pred.rewrite(context, clause_shape),
2540 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2541 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2542 SeparatorTactic::Never
2544 context.config.trailing_comma()
2547 // shape should be vertical only and only if we have `where_single_line` option enabled
2548 // and the number of items of the where clause is equal to 1
2549 let shape_tactic = if where_single_line {
2550 DefinitiveListTactic::Horizontal
2552 DefinitiveListTactic::Vertical
2555 let fmt = ListFormatting {
2556 tactic: shape_tactic,
2558 trailing_separator: comma_tactic,
2559 separator_place: SeparatorPlace::Back,
2560 shape: clause_shape,
2561 ends_with_newline: true,
2562 preserve_newline: true,
2563 config: context.config,
2565 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2567 let comment_separator = |comment: &str, shape: Shape| {
2568 if comment.is_empty() {
2571 format!("\n{}", shape.indent.to_string(context.config))
2574 let newline_before_where = comment_separator(&comment_before, shape);
2575 let newline_after_where = comment_separator(&comment_after, clause_shape);
2578 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2579 && comment_after.is_empty() && !preds_str.contains('\n')
2580 && 6 + preds_str.len() <= shape.width || where_single_line
2584 format!("\n{}", clause_shape.indent.to_string(context.config))
2587 "{}{}{}where{}{}{}{}",
2590 newline_before_where,
2591 newline_after_where,
2598 fn rewrite_where_clause(
2599 context: &RewriteContext,
2600 where_clause: &ast::WhereClause,
2601 brace_style: BraceStyle,
2605 span_end: Option<BytePos>,
2606 span_end_before_where: BytePos,
2607 where_clause_option: WhereClauseOption,
2608 is_args_multi_line: bool,
2609 ) -> Option<String> {
2610 if where_clause.predicates.is_empty() {
2611 return Some(String::new());
2614 if context.config.indent_style() == IndentStyle::Block {
2615 return rewrite_where_clause_rfc_style(
2621 span_end_before_where,
2622 where_clause_option,
2627 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2629 let offset = match context.config.indent_style() {
2630 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2631 // 6 = "where ".len()
2632 IndentStyle::Visual => shape.indent + extra_indent + 6,
2634 // FIXME: if indent_style != Visual, then the budgets below might
2635 // be out by a char or two.
2637 let budget = context.config.max_width() - offset.width();
2638 let span_start = where_clause.predicates[0].span().lo();
2639 // If we don't have the start of the next span, then use the end of the
2640 // predicates, but that means we miss comments.
2641 let len = where_clause.predicates.len();
2642 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2643 let span_end = span_end.unwrap_or(end_of_preds);
2644 let items = itemize_list(
2646 where_clause.predicates.iter(),
2649 |pred| pred.span().lo(),
2650 |pred| pred.span().hi(),
2651 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2656 let item_vec = items.collect::<Vec<_>>();
2657 // FIXME: we don't need to collect here
2658 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2660 let mut comma_tactic = context.config.trailing_comma();
2661 // Kind of a hack because we don't usually have trailing commas in where clauses.
2662 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2663 comma_tactic = SeparatorTactic::Never;
2666 let fmt = ListFormatting {
2669 trailing_separator: comma_tactic,
2670 separator_place: SeparatorPlace::Back,
2671 shape: Shape::legacy(budget, offset),
2672 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2673 preserve_newline: true,
2674 config: context.config,
2676 let preds_str = write_list(&item_vec, &fmt)?;
2678 let end_length = if terminator == "{" {
2679 // If the brace is on the next line we don't need to count it otherwise it needs two
2682 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2683 BraceStyle::PreferSameLine => 2,
2685 } else if terminator == "=" {
2690 if density == Density::Tall || preds_str.contains('\n')
2691 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2695 (shape.indent + extra_indent).to_string(context.config),
2699 Some(format!(" where {}", preds_str))
2703 fn missing_span_before_after_where(
2704 before_item_span_end: BytePos,
2705 where_clause: &ast::WhereClause,
2707 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2709 let pos_after_where = where_clause.span.lo() + BytePos(5);
2710 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2711 (missing_span_before, missing_span_after)
2714 fn rewrite_comments_before_after_where(
2715 context: &RewriteContext,
2716 span_before_where: Span,
2717 span_after_where: Span,
2719 ) -> Option<(String, String)> {
2720 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2721 let after_comment = rewrite_missing_comment(
2723 shape.block_indent(context.config.tab_spaces()),
2726 Some((before_comment, after_comment))
2729 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2730 format!("{}{}{}", format_visibility(vis), item_name, ident)
2733 #[derive(PartialEq, Eq, Clone, Copy)]
2741 context: &RewriteContext,
2742 generics: &ast::Generics,
2743 brace_style: BraceStyle,
2744 brace_pos: BracePos,
2748 ) -> Option<String> {
2749 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2750 let mut result = rewrite_generics(context, generics, shape, span)?;
2752 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2753 let budget = context.budget(last_line_used_width(&result, offset.width()));
2754 let mut option = WhereClauseOption::snuggled(&result);
2755 if brace_pos == BracePos::None {
2756 option.suppress_comma = true;
2758 // If the generics are not parameterized then generics.span.hi() == 0,
2759 // so we use span.lo(), which is the position after `struct Foo`.
2760 let span_end_before_where = if generics.is_parameterized() {
2765 let where_clause_str = rewrite_where_clause(
2767 &generics.where_clause,
2769 Shape::legacy(budget, offset.block_only()),
2773 span_end_before_where,
2777 result.push_str(&where_clause_str);
2778 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2779 || (generics.where_clause.predicates.is_empty()
2780 && trimmed_last_line_width(&result) == 1)
2782 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2783 || brace_style != BraceStyle::AlwaysNextLine
2785 if brace_pos == BracePos::None {
2786 return Some(result);
2788 let total_used_width = last_line_used_width(&result, used_width);
2789 let remaining_budget = context.budget(total_used_width);
2790 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2791 // and hence we take the closer into account as well for one line budget.
2792 // We assume that the closer has the same length as the opener.
2793 let overhead = if brace_pos == BracePos::ForceSameLine {
2800 let forbid_same_line_brace = overhead > remaining_budget;
2801 if !forbid_same_line_brace && same_line_brace {
2805 result.push_str(&offset.block_only().to_string(context.config));
2812 impl Rewrite for ast::ForeignItem {
2813 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2814 let attrs_str = self.attrs.rewrite(context, shape)?;
2815 // Drop semicolon or it will be interpreted as comment.
2816 // FIXME: this may be a faulty span from libsyntax.
2817 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2819 let item_str = match self.node {
2820 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2825 &FnSig::new(fn_decl, generics, self.vis.clone()),
2829 ).map(|(s, _)| format!("{};", s))
2831 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2832 // FIXME(#21): we're dropping potential comments in between the
2833 // function keywords here.
2834 let vis = format_visibility(&self.vis);
2835 let mut_str = if is_mutable { "mut " } else { "" };
2836 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2838 let shape = shape.sub_width(1)?;
2839 ty.rewrite(context, shape).map(|ty_str| {
2840 // 1 = space between prefix and type.
2841 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2844 let nested_indent = shape.indent.block_indent(context.config);
2845 format!("\n{}", nested_indent.to_string(context.config))
2847 format!("{}{}{};", prefix, sep, ty_str)
2850 ast::ForeignItemKind::Ty => {
2851 let vis = format_visibility(&self.vis);
2852 Some(format!("{}type {};", vis, self.ident))
2856 let missing_span = if self.attrs.is_empty() {
2857 mk_sp(self.span.lo(), self.span.lo())
2859 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2861 combine_strs_with_missing_comments(